HF RF Generator Reflected Power Reduction via Voltage Signal Binning
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Solution Overview
Problem
High frequency (HF) radio frequency (RF) generators in plasma tools experience significant reflected power, which can lead to inefficient processing of wafers and reduced control over the processing results.
Innovation Solution
A method and system that reduce reflected RF power by using a controller to receive a voltage signal from the output of a match coupled to both a low frequency (LF) RF generator and an HF RF generator. The controller divides the voltage signal into bins, identifies a bin with a zero crossing, and applies fixed multipliers to the frequency of the HF RF signal to generate negative and positive offsets, adjusting the HF RF generator's operation accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional RF generation methods are used in plasma tools, then the system can operate with standard RF generators, but significant reflected power is experienced leading to inefficient processing
Solution Approach 1:
The patent applies dynamics by making the HF RF generator frequency adjustable and variable during operation. The controller dynamically changes the frequency of the HF RF signal based on real-time voltage signal analysis and bin identification, allowing the system to adapt to changing plasma conditions and minimize reflected power continuously throughout the processing cycle
Solution Approach 2:
The patent implements parameter changes by modifying the frequency parameter of the HF RF generator. The controller applies fixed multipliers to frequency offset values to generate adjusted frequency commands, changing the operational frequency to optimize power transfer and reduce reflected power, thereby improving processing efficiency
2Manufacturing precision
If standard RF signal control is used, then the system structure remains simple, but control over plasma processing conditions is reduced
Solution Approach 1:
The patent implements feedback by using the voltage signal from the plasma chamber to control the HF RF generator frequency. The controller continuously monitors the voltage signal, identifies bins with zero crossings, and adjusts the frequency accordingly, creating a closed-loop control system that precisely controls plasma processing conditions based on real-time chamber state
Solution Approach 2:
The patent applies segmentation by dividing the voltage signal into multiple bins for analysis. The controller identifies specific bins containing zero crossings and uses this segmented information to determine frequency adjustments, allowing precise control based on different phases or portions of the voltage waveform
Data Source
AI summary
A method for reducing reflected radio frequency (RF) power is described. The method includes receiving a voltage signal from an output of a match. The method further includes dividing the voltage signal into a plurality of bins and identifying a bin from the plurality of bins that includes a zero crossing. The bin is associated with a frequency of a high frequency (HF) signal. The method also includes applying a fixed multiplier to the frequency of the HF signal to generate a plurality of offsets. The method includes operating an HF RF generator according to the plurality of offsets during a time period in which the voltage signal is positive or negative.